-PLEASE READ- These are the stats my character ended up with because I did not originally go for a PvP build. So, you do not need ATN, or INT. ATN is recommended for Forbidden Sun so you can have a long range shot invade the enemy tries to distance themselves. You need at least 3 slots to equip the sun spell. Your DEX only needs to be as high as your equipment requires it to be. All the rest of those extra points can go towards VGR, END, and VIT. Doing this might not require the +1 Soldier Ring mentioned Below. A lower tier one or a higher tier Dragon Ring is acceptable.
Drakekeeper's Greathammer +10 (Infuse Optional) or any strike based weapon. A heavy slash weapon is a good alternative but a lot of armors are weak to strike. Pyro Flame +10, Witchtree Branch, and Rebel's Greatshield +10 with magic infuse. You should level up all of your weapons as high as possible for more damage except for the Branch. There's no need to level it up.
Velstadt's armor leveled up as high as you can. Requires Twinkling Titanite which will make leveling take a while. Level the chest piece first. Chloranthy ring and the Royal Soldier Ring +1 are crucial. Otherwise you will fat roll without the +1 The Dispelling Ring is almost important to raise your magic, dark, fire, and lightning damage since Velstadt armor has low elemental defense. The forth ring can be Thunder Quartz, a Dragon ring, or your covenant ring would be useful when invading. A ring of Life Protection for being invaded if you don't wish to lose your humanity. A ring of Binding is a good alternative being that it keeps your health at 80% no matter how much you die.
Forbidden Sun is good to finish people off if they are at a range. Great Magic Weapon will imbue your hammer with magic to make it more effective.
Remember to time your attacks carefully because you will swing quite slow. Take a close look at how the enemy moves and fights, including how long it takes to set up their attacks. For example, if they use firestorm, you can back off and switch to your Pyro Glove to cast the Sun spell since it fires quickly. Take advantage of their slow movements. Remain close to them but not close enough for them to guard break. If they run, pursue them and keep them in sight ready to use the sun spell incase they try to heal.